1. Field of the Invention
The invention relates to a rotary cutting tool and holder having an internal channel for coolant/lubricant extending axially through the holder and the cutting tool.
2. Prior Art
It is known to use extended holders and replaceable cutting tools for different types of cutting and cutting operations, such as drilling, milling, machining and the like with internal channels for the passage of coolants and/or lubricants to the cutting edge. However, the prior art devices are often unstable at high rotational speeds as a result of vibration due to imbalance. Furthermore, the replacement of cutting tools for maintenance or other purposes is often inconvenient, resulting in greater amounts of down time when it is necessary to replace a cutting tool.
U.S. Pat. No. 4,950,108 to Roos discloses a drill having replaceable drill tips and a central channel for the passage of flushing fluid.
U.S. Pat. No. 5,599,145 to Reinauer et al. discloses a drill comprising a cylindrical holder and having interchangeable cutting inserts and internal coolant channels.
U.S. Pat. No. 5,851,094 to Strand et al. discloses a milling tool comprising a shank defining an axis of rotation with a replaceable cutting head mounted in the shank and a central channel for the transmission of flushing medium.
U.S. Pat. No. 5,980,166 to Ogura discloses a rotary tool, such as a drill, with a shank having a narrow internal channel for the transmission of fluid.
It is an object of the present invention to provide a rotary cutting tool and holder wherein the cutting tool can be conveniently removed and replaced for maintenance or other purposes.
It is a further object to provide a rotary cutting tool and holder wherein the cutting tool can be selected from various interchangeable cutting tools for various purposes.
It is a still further object to provide a rotary cutting tool holder and conveniently replaceable cutting tools and having an internal channel for the transmission of fluid, such as coolants to the cutting surface.
The above and other objects are accomplished in accordance with the present invention which provides a rotary cutting tool and holder wherein the holder comprises
A) an elongated shank, defining an axis of rotation, and having an internal channel along the axis of rotation, and forming at one end thereof, a tapered seat adapted to receive a rotary cutting tool;
B) a thru pin adapted to fit within said channel and having an internal bore along the length thereof for the passage of liquid therethrough, and having an external male threaded end adapted to be positioned centrally within the tapered seat when the thru pin is in position within the channel; and the rotary cutting tool comprises a cutting end and an attachment end, the attachment end having a tapered external shape, adapted to fit conformably within the tapered seat of the holder, and an internal female thread adapted to engage the external male threaded end of the thru pin.
In assembling the cutting tool and holder, the thru pin is positioned within the holder and the threaded end of the thru pin is screwed into the internal thread of the attachment end of the cutting tool holding it tightly in place against the tapered seat. In one embodiment the tapered seat and conformably tapered attachment end of the cutting tool may be rectangular in cross-sectional shape. In this case the external threads of the thru pin may be screwed into the cutting tool by turning the thru pin for example with the aid of an Allen wrench and an Allen fitting at the opposite end of the thru pin. In a preferred embodiment, the tapered seat in the holder is conical, that is, having a circular cross-sectional shape and the cutting tool can be turned as it enters the seat, to screw it onto the threaded end of the thru pin until the attachment end of the cutting tool is pulled tight against the seat.
The cutting end of the rotary cutting tool may be designed for various conventional operations utilizing rotary tools, for example, for drilling, milling, cutting, grinding, sawing, or other such operations generally known to those skilled in the art.